POY was looking funny, and the YARM wasn't locking.  It looked like POY wasn't seeing any light at all.  I went to check, and it looks like a beam dump got accidentally placed in the POY path during oplev adjustments this morning.  POY is back, locking continues.

As discussed in the meeting, I removed the extra beam splitter that dumps most of the beam going towards WFS photodiodes. This beam splitter needs to be placed back in position before increasing the input power to IMC at nominal level. This is to get sufficient light on the WFS photodiodes so that we can keep IMC locked for more than 3 days. Currently IMC is unlocked and misaligned. I have marked the position of this beam splitter on the table, so putting it back in should be easy. Right now, I'm trying to align the mode cleaner back and start the WFS loops once we get it locked.

Problem:

Way back, Jay had D-sub to SCSI adapters made to adapt our existing Sander box AA filters to the new SCSI based IO chassis.  However, these did not fit inside the box.

At the time, we simply left the cards outside hanging, which was a hack and needed to be replaced.

Solution:

Steve modified a black AA filter box so that it could fit the D-sub to SCSI adapter board on it, plus strain relief the SCSI cable, rather than let it hang.  The back of the box was cut, and an extending piece of metal attached to the bottom of the box.  The adapter board was screwed into the box, the SCSI plugged in, then the SCSI cable is clamped to the extending metal as well.

This modification will be propagated to the 3 remaining AA filter boards using the D-sub to SCSI adapter.

 The same modification was carried out at 1X5 for PRM & SRM.

Note:  D68L8EX-850Hz  are removed  and bypassed in 7 channels.

Because it was driving me crazy while working on the new medm screens for the simulated plant, I went and removed the aliased font entries in /usr/share/X11/fonts/misc/fonts.alias that are associated with medm.  Specifically I removed the lines  starting with widgetDM_.  I made a backup in the same directory called fonts.alias.bak with the old lines.

Medm now behaves the same on op440m, rosalba, and allegra - i.e. it can't find the widgetDM_ scalable fonts and defaults to a legible fixed font.

[Tega, Anchal]

c1mcs and c1ioo models have been updated to add new acquisition of data.

IOO:WFS channels

We found from https://ldvw.ligo.caltech.edu/ldvw/view that following channels with "WFS" in them are acquired at the sites:

• :IOO-WFS1_IP
• :IOO-WFS1_IY
• :IOO-WFS2_IP
• :IOO-WFS2_IY

These are most probably error signals of WFS1 and WFS2. At 40m, we have following channel names instead:

• C1:IOO-WFS1_I_PIT_OUT
• C1:IOO-WFS1_I_YAW_OUT
• C1:IOO-WFS2_I_PIT_OUT
• C1:IOO-WFS2_I_YAW_OUT

And similar for Q outputs as well. We also have chosen quadrature signals (signals after sensing matrix) at:

• C1:IOO-WFS1_PIT_OUT
• C1:IOO-WFS1_YAW_OUT
• C1:IOO-WFS2_PIT_OUT
• C1:IOO-WFS2_YAW_OUT

We added following testpoints and are acquiruing them at 1024 Hz:

• C1:IOO-WFS1_IP  (same as C1:IOO-WFS1_I_PIT_OUT)
• C1:IOO-WFS1_IY  (same as C1:IOO-WFS1_I_YAW_OUT)
• C1:IOO-WFS2_IP  (same as C1:IOO-WFS2_I_PIT_OUT)
• C1:IOO-WFS2_IY  (same as C1:IOO-WFS2_I_YAW_OUT)

IOO-MC_TRANS

For the transmission QPD at MC2, we found following acquired channels at the site:

• :IOO-MC_TRANS_DC
• :IOO-MC_TRANS_P
• :IOO-MC_TRANS_Y

We created testpoints in c1mcs.mdl to add these channel names and acquire them. Following channels are now available at 1024 Hz:

• C1:IOO-MC_TRANS_DC
• C1:IOO-MC_TRANS_P
• C1:IOO-MC_TRANS_Y

We started acquiring following channels for the 6 error signals at 1024 Hz:

• C1:IOO-WFS1_PIT_IN1
• C1:IOO-WFS1_YAW_IN1
• C1:IOO-WFS2_PIT_IN1
• C1:IOO-WFS2_YAW_IN1
• C1:IOO-MC2_TRANS_PIT_IN1
• C1:IOO-MC2_TRANS_YAW_IN1

We started acquiring following 6 control signals at 1024 Hz as well:

• C1:IOO-MC1_PIT_OUT
• C1:IOO-MC1_YAW_OUT
• C1:IOO-MC2_PIT_OUT
• C1:IOO-MC2_YAW_OUT
• C1:IOO-MC3_PIT_OUT
• C1:IOO-MC3_YAW_OUT

RXA: useful to know that you have to append "_DQ" to all of the channel names above if you want to find them with nds2-client.

Other changes:

In order to get C1:IOO-MC_TRANS_[DC/P/Y], we had to get rid of same named EPICS output channels in the model. These were been acquired at 16 Hz before this way. We then updated medm screens and autolocker config file. For slow outputs of these channels, we are using C1:IOO-MC_TRANS_[PIT/YAW/SUMFILT]_OUTPUT now. We had to restart daqd service for changes to take effect. This can be done by sshing into fb1 and running:

Now there is a convinient button present in FE overview status medm screen to restart DAQD service by a simple click.

Frank noticed that this particular SR560 had an offset on the output which was unzeroable by the usual method of tuning the trim pot accessible through the front panel.

I tried to zero the offset using the trimpots inside, but it became clear that the offset was due to a damaged FET, so Steve ordered ~20 of the (now obsolete*) NPD5564.

I replaced this part and adjusted the offsets and balanced the CMRR of the differential inputs mostly according to the manual (p. 17). There are a few notes that should be added to the procedure:

1. It can sometimes be that the gain proscribed by the manual is too high and saturates the output for large offsets. If that's the case, simply lower the gain, trim the offset, then return the gain to the specified value and trim again.
2. The limit in trimming the offset is the stick slip resolution in the trim pot. This can potentially leave the whole preamp in an acoustically sensitive state. I tapped the pots with a screwdriver after tuning to make sure it was in more of a 'sticky' rather than 'slippy' region of the knob. A better design would allow for more filtering of the pot.
3. In the CMRR tuning procedure it says to 'null sine wave output' but it should really say 'null the sine wave component at the drive frequency'. The best CMRR tuning uses a 1 kHz drive and leaves a residual 2 kHz signal due to the distortion imbalance (of the FETs I think).
4. The CMRR tuning upsets the DC offset trim and vice versa. The best tuning is gotten by iterating slightly (go back and forth once or twice between the offset and CMRR tuning procedures).

It looks like its working fine now. Steve's ordering some IF3602 (low-noise, balanced FET pair from Interfet) to see if we can drop the SR560's input noise to the sub-nV level.

Noise measured with the input terminated with a BNC short (not 50 Ohms) G=100, DC coupled, low-noise mode:

[ericq,Jenne]

Since we don't have agreement between the measurements we made the other day and the earlier estimations, I wanted to repeat the demodulation angle measurement. We had to do a few things to keep the PRMI locked, since in the last few days, it hasn't been stable enough.

The mode cleaner had been very fussy lately; the WFS were pushing in a way that caused fast oscillations of the transmission and reflection powers. I turned off the servos, manually aligned the mode cleaner to transmission of about 15k and refl of about .4, centered the beams on the WFS QPDs, and turned the loops back on. Things were much stable after that. Also, Jenne noticed that the PMC loop had walked the laser PZT temperature to a bad place, and fixed it.

After aligning the carrier locked PRMI, the last piece needed to get things stable enough for sideband locking was turning off the angular damping on the PRM suspension screen (this was turned back on when we were done). Waiting until evening noise levels probably helped too. We used a 1000 count MICH excitation in the PRMI case, and recorded data for about a minute in one degree steps around the demodulation phase that looked to put the excitation entirely within the Q of the PD. Also, we notched out the excitation frequency in the MICH servo bank for today's measurement; I think it's outside of the loop bandwidth anyways, but it's good to be sure. 

Jenne and I pondered a bit whether changing the AS55 demodulation phase while it (AS55 Q) is being used as the MICH control signal introduces subtleties that we haven't anticipated, but couldn't come up with anything concrete. Changing the angle from the what maximizes the Q just looks like a slight change in MICH gain, and shouldn't affect the phase of the excitation signal on the PD...

In any case, the data have been recorded, and the results will follow soon. 

Method

Since I am mainly concerned with the actuator part of the OSEM, I chose to do this measurement at the output cables for the coil drivers in 1X4. See schematic for pin-mapping. There are several parts in between my measurement point and the actual coils but I figured it's a good check to figure out if measurements made from this point yield sensible results. The slow bias voltages were ramped off under damping (to avoid un-necessarily kicking the optics when disconnecting cables) and then the suspension watchdogs were shutdown for the duration of the measurement.

I used an LCR meter to measure R and L - as prescribed by Koji, the probe leads were shorted and the readback nulled to return 0. Then for R, I corroborated the values measured with the LCR meter against a Fluke DMM (they turned out to be within +/- 0.5 ohms of the value reported by the BK Precision LCR meter which I think is reasonable).

Result

Conclusions

On the basis of this measurement, I see no problems with the OSEM actuators - the wire resistances to the flange seem comparable to the nominal OSEM resistance of ~13 ohms, but this isn't outrageous I guess. But I don't know how to reconcile this with Koji's measurement at the flange - I guess I can't definitively rule out the wire resistance being 30 ohms and the OSEMs being ~1 ohm as Koji measured. How to reconcile this with the funky PRM actuator measurement? Possibilities, the way I see it, are:

1. Magnets on PRM are weird in some way. Note that the free-swinging measurement for the PRM showed some unexpected features.
2. The imbalance is coming from one of the drive chain - could be a busted current buffer for example.
3. The measurement technique was wrong.

I broke a small bit while using the 40m drill press to vent some 1/4-20 screws for the cryo experiment.

I replaced it and refilled the small bit row in the bit index I was using; there were ~10 missing sizes

[Steve, Masayuki]

We replaced the laser for optical lever of ETMY. And also we aligned the path so that beam spot hits the center for each optics. I attached the spectrum of the SUS-ETMY_OPLEV_SUM, the red curve is with old laser, and blue curve is with the new laser. We also measured without laser so as to measure the QPD dark noise (green curve). The change is significant, and seems much closer to other oplev spectrum.(Brown curve is the oplev spectrum of ITMY)

The new laser is:

Manufacture name: JDSU, Model number: 1103P, Serial number: PA892324

The injection power is 3.7 mW and the out coming power is 197 uW (measured just before the QPD). The output value of the SUS-ETMY_OPLEV_SUM is about 8500.

First we measure 2 spectrum ( including the dark noise). After that we replace the laser and align the optical lever path. We changed the post of one of the mirror (just before the QPD) because the hight was too low. Inside of the chamber is darker than before - actually we had scattering light inside the chamber before. We dumped the reflected light from QPD. And then we measured the spectrum of the oplev output. I also aligned oplev of ETMY after restoring the YARM configuration using IFO configure screen.

We don't know actually what was the problem, laser quality or the scattering light or some clipping. But the oplev seems to be better.

Steve:  Atm2 shows increased gains correction later for UGF elog 9206

  That's good, but please no more Oplev work. We want to do all of it at once and to make no more changes until we have all the parts (e.g. dumps and correct lenses) in hand and then talk over what the new design will be. I don't want to tune the beam size and loop shape every week.

I centered the ETMY OL today and found that the UGF was around 3-4x too LOW after the laser swap and re-alignment. That's why the Y arm has been shaking so much today.

NO more OL work without loop measurements and noise measurements.

 Just plot.

RA: I'm not sure how to interperet this; I think that the SUM channel is divided by the SUM so that this is supposed to be RIN, but not sure. Can someone please take a look into the SUS model and then explain in the elog what the SUM normalization algorithm is?

I have found two great FET input chips that rival the storied, discontinued AD743. In some ways, they are even better. These parts are the OPA140 and the OPA827.

Below is a plot of the input-referred voltage noise of the two op amps with R_source = 0, along with several others for comparison. The smooth traces are LISO models. The LT1128 and AD797 are BJT-input parts, so their voltage noise is naturally better. However, the performance you see here for the FET parts is the same you would expect for very large source impedances, due to their extremely low current noise by comparison. I have included the BJTs so that you can see what their performance is like in an absolute sense. I have also included a "measured" trace of the LT1128, since in practice their low-frequency noise can be quite higher than the spec (see, for example, Rana's evaluation of the Busby Box). The ADA4627 is another part I was looking into before, the LT1012 is a less-than-great FET chip, and the AD797 a less-than-great BJT.

As you can see, the OPA140 actually outperforms the AD743 at low frequencies, though it is ~2x worse at high frequencies. The OPA827 comes close to the AD743 at high frequencies, but is a bit worse at low ones. Both the OPA140 and OPA827 have the same low-frequency RMS spec, so I was hoping it would be a better all-around part, but, unfortunately, it seems not to be.

The TI chips also have a few more things on the AD743:

• Input current noise @ 1kHz
  • AD743: 6.9 fA/rtHz
  • OPA827: 2.2 fA/rtHz
  • OPA140: 0.8 fA/rtHz (!)
• Input bias (offset) current, typ
  • AD743: 30 pA (40 pA) --- only for V_supply = ±5 V
  • OPA827: ±3 pA (±3 pA) --- up to ±18V
  • OPA140: ±0.5 pA (±0.5 pA) (!) --- up to ±18V
• Supply
  • Both OPA140 and OPA827 can be fed single supplies up to 36V absolute maximum
  • The OPA140 is a rail-to-rail op amp

These characteristics make both parts exceptionally well suited for very-high source impedance applications, such as very-low-frequency AC-coupling preamplifiers or ultra-low-noise current sources.

(Apologies---the SR785 I was using had some annoying non-stationary peaks coming in. I verified that they did not affect the broadband floor).

R.I.P., AD743

Rana suggested that I measure the OPA827 and OPA140 noise with high source impedance so as to see if we could find the low-frequency current noise corner. Below is a plot of both parts with R_s = 0, 10k, and 100k.

As you can see, both parts are thermal noise limited down to 0.1 Hz for up to R_s = 100k or greater. Given that the broadband current noise level for each part is ~0.5-1 fA/rtHz, this puts an upper limit to the 1/f corner of <100 Hz. This is where the AD743 corner is, so that sounds reasonable. Perhaps I will check with even higher impedance to see if I can find it. I am not sure yet what to make of the ~10-20 kHz instability with high source impedance.

EDIT: The datasheets claim that they are Johnson noise limited up to 1 Mohm, but this is only for the broadband floor, I'd guess, so it doesn't really say anything about the low frequency corner.

  This looks pretty good already. Not sure if we can even measure anything reasonable below 0.1 Hz without a lot of thermal shielding.

The 10-20 kHz oscillation may just be the loop shape of the opamp. I think you saw similar effects when using the AD743 with high impedance for the OSEM testing.

There has been an ongoing memory error in optimus with the following messages:

controls@optimus|~ >
Message from syslogd@optimus at Jun 30 14:57:48 ...
 kernel:[1292439.705127] [Hardware Error]: Corrected error, no action required.

Message from syslogd@optimus at Jun 30 14:57:48 ...
 kernel:[1292439.705174] [Hardware Error]: CPU:24 (10:4:2) MC4_STATUS[Over|CE|MiscV|-|AddrV|CECC]: 0xdc04410032080a13

Message from syslogd@optimus at Jun 30 14:57:48 ...
 kernel:[1292439.705237] [Hardware Error]: MC4_ADDR: 0x0000001ad2bd06d0

Message from syslogd@optimus at Jun 30 14:57:48 ...
 kernel:[1292439.705264] [Hardware Error]: MC4 Error (node 6): DRAM ECC error detected on the NB.

Message from syslogd@optimus at Jun 30 14:57:48 ...
 kernel:[1292439.705323] [Hardware Error]: cache level: L3/GEN, mem/io: MEM, mem-tx: RD, part-proc: RES (no timeout)

Optimus is a Sun Fire X4600 M2 Split-Plane server. Based on this message, the issue seems to be in memory controller (MC) 6, chip set row (csrow) 7, channel 0. I got this same result again after installing edac-utils and running edac-util -v, which gave me:

mc6: csrow7: mc#6csrow#7channel#0: 287 Corrected Errors 

and said that all other DIMMs were working fine with 0 errors. Each MC has 4 csrows numbered 4-7. I shut off optimus and checked inside and found that it consists of 8 CPU slots lined up horizontally, each with 4 DIMMs stacked vertically and 4 empty DIMM slots beneath. I'm thinking that each of the 8 CPU slots has its own memory controller (0-7) and that the csrow corresponds to the position in the vertical stack, with csrow 7 being the topmost DIMM in the stack. This would mean that MC 6, csrow 7 would be the 7th memory controller, topmost DIMM. The channel would then correspond to which one of the DIMMs in the pair is faulty although if the DIMM was replaced, both channels 0 and 1 would be switched out. Here are some sources that I used:

http://docs.oracle.com/cd/E19121-01/sf.x4600/819-4342-18/html/z40007f01291423.html#i1287456

https://siliconmechanics.zendesk.com/hc/en-us/articles/208891966-Identify-Bad-DIMM-from-EDAC

http://martinstumpf.com/how-to-diagnose-memory-errors-on-amd-x86_64-using-edac/

I'll find the exact part needed to replace soon.

Optimus' memory errors are back so I found the exact DIMM model needed to replace: http://www.ebay.com/itm/Lot-of-10-Samsung-4GB-2Rx4-PC2-5300P-555-12-L0-M393T5160QZA-CE6-ECC-Memory-/201604698112?hash=item2ef0939000:g:EgEAAOSwqBJXWFZh I'm not sure what website would be the best for buying new DIMMs but this is the part we need: Samsung 4GB 2Rx4 PC2-5300P-555-12-L0 M393T5160QZA-CE6.

I replaced the suspected faulty DIMM earlier today (actually I replaced a pair of them as per the Sun Fire X4600 manual). I did things in the following sequence, which was the recommended set of steps according to the maintenance manual and also the set of graphics on the top panel of the unit:

1. Checked that Optimus was shut down
2. Removed the power cables from the back to cut the standby power. Two of the fan units near the front of the chassis were displaying fault lights, perhaps this has been the case since the most recent power outage after which I did not reboot Optimus
3. Took off the top cover, removed CPU 6 (labelled "G" in the unit). The manual recommends finding faulty DIMMs by looking for an LED that is supposed to indicate the location of the bad card, but I couldn't find any such LEDs in the unit we have, perhaps this is an addition to the newer modules?
4. Replaced the topmost (w.r.t the orientation the CPU normally sits inside the chassis) DIMM card with one of the new ones Steve ordered
5. Put everything back together, powered Optimus up again. Reboot went smoothly, fan unit fault lights which I mentioned earlier did not light up on the reboot so that doesn't look like an issue.

I then checked for memory errors using edac-utils, and over the last couple of hours, found no errors (corrected or otherwise, see Praful's earlier elog for the error messages that we were getting prior to the DIMM swap)- I guess we will need to monitor this for a while more before we can say that the issue has been resolved.

Looking at dmesg after the reboot, I noticed the following error messages (not related to the memory issue I think):

[   19.375865] k10temp 0000:00:18.3: unreliable CPU thermal sensor; monitoring disabled
[   19.375996] k10temp 0000:00:19.3: unreliable CPU thermal sensor; monitoring disabled
[   19.376234] k10temp 0000:00:1a.3: unreliable CPU thermal sensor; monitoring disabled
[   19.376362] k10temp 0000:00:1b.3: unreliable CPU thermal sensor; monitoring disabled
[   19.376673] k10temp 0000:00:1c.3: unreliable CPU thermal sensor; monitoring disabled
[   19.376816] k10temp 0000:00:1d.3: unreliable CPU thermal sensor; monitoring disabled
[   19.376960] k10temp 0000:00:1e.3: unreliable CPU thermal sensor; monitoring disabled
[   19.377152] k10temp 0000:00:1f.3: unreliable CPU thermal sensor; monitoring disabled

I wonder if this could explain why the fans on Optimus often go into overdrive and make a racket? For the moment, the fan volume seems normal, comparable to the other SunFire X4600s we have running like megatron and FB...

I did apt-get update and then apt-get upgrade on optimus. All systems are nominal.

Assembled is the list of dead pressure gauges. Their locations are also circled in Attachment 1.

For replacements, I recommend we consider the Agilent FRG-700 Pirani Inverted Magnetron Gauge. It uses dual sensing techniques to cover a broad pressure range from 3e-9 torr to atmosphere in a single unit. Although these are more expensive, I think we would net save money by not having to purchase two separate gauges (Pirani + hot/cold cathode) for each location. It would also simplify the digital controls and interlocking to have a streamlined set of pressure readbacks.

For controllers, there are two options with either serial RS232/485 or Ethernet outputs. We probably want the Agilent XGS-600, as it can handle all the gauges in our system (up to 12) in a single controller and no new software development is needed to interface it with the slow controls.

Now that the new Agilent full-range gauges (FRGs) have been received, I'm putting together an installation plan. Since my last planning note in Sept. (ELOG 15577), two more gauges appear to be malfunctioning: CC2 and PAN. Those are taken into account, as well. Below are the proposed changes for all the sensors in the system.

In summary:

• Four of the FRGs will replace CC1/2/3/4.
• The fifth FRG will replace CCMC if the 15.6 m cable (the longest available) will reach that location.
• P2 and P3 will be moved to replace PTP1 and PAN, as they will be redundant once the new FRGs are installed.

Required hardware:

• 3x CF 2.75" blanks
• 10x CF 2.75" gaskets
• Bolts and nut plates

Update to the gauge replacement plan (15692), based on Jordan's walk-through today. He confirmed:

• All of the gauges being replaced are mounted via 2.75" ConFlat flange. The new FRGs have the same footprint, so no adapters are required.
• The longest Agilent cable (50 ft) will NOT reach the CCMC location. The fifth FRG will have to be installed somewhere closer to the X-end.

Based on this info (and also info from Gautam that the PAN gauge is still working), I've updated the plan as follows. In summary, I now propose we install the fifth FRG in the TP1 foreline (PTP1 location) and leave P2 and P3 where they are, as they are no longer needed elsewhere. Any comments on this plan? I plan to order all the necessary gaskets, blanks, etc. tomorrow.

The 24 V Sorenson (2nd from bottom) in the small rack west of 1x2 was repurposed to 12V 600 mA, and was run to a terminal block on the north side of 1X1. Cables were routed underneath 1X1 and 1X2 to the terminal blocks. 12V was then routed to the PSL table and banana clip terminals were added.

[Yehonathan, Yuta, Paco]

We would like to estimate:

• LO phase sensitivty (for RF55 + audio dither scheme), as a function of RF demod angle (both I and Q); not to be confused with audio dither angle.
• LO phase sensitivity (for all schemes like in Attachment #2 of this previous post) but with some nonzero MICH offset.
• LO phase sensitivity (for RF55 + audio dither scheme) but with the uBHDBS (44:56) values from this post.

For the 40m Upgrade, we plan to eliminate the Mach-Zehnder and replace it with a single EOM driven by all three modulation frequencies that we'll need: f1=11MHz, f2=5*f1=55MHz, fmc=29.5MHz.

A frequency generator will produce the three frequencies and with some other electronics we'll properly combine and feed them to the EOM.

The frequency generator will have two crystals to produce the f1 and fmc signals. The f2 modulation will be obtained by a frequency multiplier (5x) from the f1.

The frequency multiplier, for the way it works, will inevitably introduce some unwanted harmonics into the signals. These will show up as extra modulation frequencies in the EOM.

In order to quantify the effects of such unwanted harmonics on the interferometer and thus to let us set some limits on their amplitude, I ran some simulations with Optickle. The way the EOM is represented is by three RF modulators in series. In order to introduce the unwanted harmonics, I just added an RF modulator in series for each of them. I also made sure not to leave any space in between the modulators, so not to introduce phase shifts.

To check the effect at DC I looked at the sensing matrix and at the error signals. I considered the 3f error signals that we plan to use for the short DOFs and looked at how they depend on the CARM offset. I repeated the simulations for several possible amplitude of the unwanted harmonics. Some results are shown in the plots attached to this entry. 'ga' is the amplitude ratio of the unwanted harmonics relative to the amplitude of the 11 & 55 MHz modulations.

Comparing to the case where there are no unwanted harmonics (ga = 0), one can see that not considerable effect on the error signals for amplitudes 40dB smaller than that of the main sidebands. Above that value, the REFL31I signals, that we're going to use to control PRCL, will start to be distorted: gain and linearity range change.

So 40 dB of attenuation in the unwanted harmonics is probably the minimum requirement on the frequency multiplier, although 60dB would provide a safer margin.

I'm still thinking how to evaluate any AC effect on the IFO.

** TODO: Plot DC sweeps with a wider range (+/- 20 pm). Also plot swept sines to look for changes in TFs out to ~10 kHz.

 I re-routed around the c1lsc machine this morning.  I turned the crate off, and disconnected the transmission fiber from  c1lsc (which went to the receiver on c1asc).  I then took the receiving fiber from c1lsc and plugged it into the receiver on c1asc. 

I pulled out the c1lsc computer from the VME crate and pulled out the RFM card, which I needed for the CDS upgrade.  I then replaced the lsc card back in the crate and turned it back on.  Since there hasn't been a working version of the LSC code on linux1 since I overwrote it with the new CDS lsc code, this shouldn't have any significant impact on the interferometer.

I've confirmed that the RFM network seems to be in a good state (the only red lights on the RFM timing and status medm screen are LSC, ASC, and ETMX).  Fast channels can still be seen with dataviewer and fb40m appears to still be happy.

The RFM card has found its new home in the SUS IO Chassis.  The short fiber that used to go between c1asc and c1lsc is now on the top shelf of the new 1X3 rack.

 I just realized that an unfortunate casualty of this LSC work was the deletion of the slow controls for the LSC which we still use (some sort of AUX processor). For example, the modulation

depth slider for the MC is now in an unknown state.

If you're refering to just the medm screen,  those can be restored from the SVN.  As we're moving to a new directory structure, starting with /opt/rtcds/caltech/c1/, the old LSC screens can all be put back in the /cvs/cds/caltech/medm/c1/lsc directory if desired.

The slow lsc aux crate, c1iscaux2, is still working, and those channels are still available.  I confirmed that one was still updating. As a quick test, I went to the SVN and pulled out the C1LSC_RFADJUST.adl file, renamed it to C1LSC_RFadjust.adl and placed it in /cvs/cds/caltech/medm/c1/lsc/, and checked it linked properly from the C1IOO_ModeCleaner.adl file.  I haven't touched the modulation depths, as I didn't want to mess with the mode cleaner, but if I get an OK, we can test that today and confirm that modulation depth control is still working.

Fridge brought back inside.

After Koji and I reset the transmission normalizations last Friday, he did some alignment work that increased the Yarm power.  So, I had set the transmission normalization when we weren't really at full Yarm power.  Today I reset the normalization so that instead of ~1.2, the Y transmission PDs read ~1.0.

OD     = 0.0036" =  0.091 mm
Length = 46"     = 1168.4 mm
Resistance     =   33.3 Ohms

resistivity = R * pi * (OD/2)^2
              ----------------- = 1.85e-7 Ohm-meters
                  Length 

                  resistivity (Ohm-meter x 10^-7)
-------------     ----------------
304 Stainless       7.2
316 Stainless       7.4
Cast Steel          1.6

I claim that neither of those things is plausible.  We took out 1 PZT, and put in 1 active TT onto the BS table.  There is no way the resonant frequency changed by an appreciable amount due to that switch.

I don't think that it is the resonant frequency of the TTs either.  Here, I collate the data that we have on the resonant frequencies of our tip tilts.  It appears that in elog 3425 I recorded results for TTs 2 and 3, but in elog 3447 I just noted that the measurements had been done, and never put them into the elog.  Ooops.

Resonant frequency and Q of modes of passive tip tilts. 

Notes:  "Serial Number" of TTs here is based on the SN of the top suspension point block.  This does not give info about which TT is where.  Pitch modes were all too low of Q to be measured, although we tried.

Tip tilt mode measurements were taken with a HeNe and PD shadow sensor setup - the TT's optic holder ring was partially obscuring the beam.

[JC, Anchal, Yuta]

We are working on resonant frequency idendification from the free swing test done last weekend.
Table below is the resonant frequencies identified, and attached are the plots of peak identification for some of our new suspensions.
To identify the resonant frequencies, the kicks were done in each degrees of freedom so that we can assume, for example, SUSPOS will be mostly excited when kicked in POS and the heighest peak is at the POS resonant frequency.
For PR3, AS1 and ETMY, the resonant frequency idendification needs to be done in the order of POS, PIT, YAW, SIDE and identified frequencies need to be removed when finding a peak.
Other than that, the identification was done without any prior assumptions on the suspensions.
For ITMY, ETMY, PR2, PR3, AS1, AS4, yaw has lower resonant frequencies than pitch, as opposed to other suspensions.
For LO1, POS and PIT frequencies might be swapped because LLCOIL is not working (40m/16898) and POS/PIT kicks both might be excited SUSPOS/PIT.
LO1 coil output matrix was temporarily modified so that we use only two coils for POS/PIT/YAW excitation (Attachment #7), as we did for ITMY (40m/16899).

The scripts for the free swinging test and analysis live in /Git/40m/scripts/SUS/InMatCalc

     POS    PIT    YAW    SIDE
BS   0.990  0.748  0.794  0.959 
ITMY 0.987  0.739  0.634  0.948 fPIT > fYAW
ETMY 0.979  0.816  0.649  0.954 fPIT > fYAW
ITMX 0.978  0.586  0.758  0.959 
ETMX 0.962  0.725  0.847  1.000 
PRM  0.939  0.541  0.742  0.990 
PR3  1.019  0.885  0.751  0.989 fPIT > fYAW
PR2  0.996  0.816  0.724  0.999 fPIT > fYAW
SRM  0.969  0.533  0.815  0.985 
SR2  0.978  0.720  0.776  0.997 
LO1  0.926  1.011  0.669  0.993 POS AND PIT MIGHT BE SWAPPED
LO2  0.964  0.998  0.995  0.990 WRONG DUE TO STUCK (40m/16913)
AS1  1.028  0.832  0.668  0.988 fPIT > fYAW
AS4  1.015  0.800  0.659  0.991 fPIT > fYAW
MC1  0.967  0.678  0.797  0.995 
MC2  0.968  0.748  0.815  0.990 
MC3  0.978  0.770  0.841  0.969 

Every so often things just work out. You do the calculations, you put the lenses on the bench, you manually adjust the pointing and fiddle with the lenses a bit, you get massive chunks of assistance from Kiwamu to get the alignment controls and monitors set up and after quite a bit of fiddling and tweaking the cavity mirror alignment you might get some nice TEM_00 -like shapes showing up on your Y-arm video monitors.

So. We have resonating green light in the Y-arm. The beam is horribly off-axis and the mode-matching, while close enough to give decent looking spots, has in no way been optimised yet. Things to do tomorrow - fix the off-cavity-axis problem and tweak up the mode-matching... then start looking at the locking...

 Koji asked me to perform a simulation of the response of POP QPD DC signal to mirror motions, as a function of the CARM offset. Later than promised, here are the first round of results.

I simulated a double cavity, and the PRC is folded with parameters close to the 40m configuration. POP is extracted in transmission of PR2 (1ppm, forward beam). For the moment I just placed the QPD one meter from PR2, if needed we can adjust the Gouy phase. There are two QPDs in the simulation: one senses all the field coming out in POP, the other one is filtered to sense only the contribution from the carrier field. The difference can be used to compute what a POP_2F_QPD would sense. All mirrors are moved at 1 Hz and the QPD signals are simulated:

This shows the signal on the POP QPD when all fields (carrier and 55 MHz sidebands) are sensed. This is what a real DC QPD will see. As expected at low offset ETM is dominant, while at large offset the PRC mirrors are dominant. It's interesting to note that for any mirror, there is one offset where the signal disappears.

This is the contribution coming only from the carrier. This is what an ideal QPD with an optical low pass will sense. The contribution from the carrier increases with decreasing offset, as expected since there is more power.

Finally, this is what a 2F QPD will sense. The contribution is always dominated by the PRC mirrors, and the ETM is negligible.

The zeros in the real QPD signal is clearly coming from a  cancellation of the contributions from carrier and sidebands.

The code is attached.

For several MICH offsets, I measured the response of REFL33Q, ASDC and the ratio ASDC/POPDC to a MICH EXC. It appears that there is no frequency-dependent effect. The plots for MICH_OFFSET = 0.0 and 2.0 are slightly lower in magnitude: the reason is they were the first measurements done, and after that a little realignment of BS was necessary, so probably that is the reason.

Amplitude of 29.485MHz input sine wave [dBm]    |        Value of channel C1:IOO-MC_DEMOD_LO
--------------------------------------------    |        -----------------------------------
-10                                             |        -0.000449867
-8                                              |        -0.000449867
-6                                              |        -0.000449867
-4                                              |        0.000384331
-2                                              |        0.00526733
0                                               |        0.0199163
2                                               |        0.0492143
4                                               |        0.0931613
6                                               |        0.161523
8                                               |        0.229885
10                                              |        0.293364

I restarted the frame builder at the following times

Tue Sep 13 14:53:49 PDT 2011

Tue Sep 13 16:46:32 PDT 2011

Tue Sep 13 17:24:16 PDT 2011

Restarted backup since fb40m was rebooted.

Elog restart script killed the elog, but didn't restart it.  Restarted by hand.

I've noticed that it always takes running the script twice for it to actually work. I think there's something wrong with how it's doing it. I'll mess with it sometime the elog isn't getting much use.

with the script, as it was down.

Again.

Fb is now once again actually recording trends.

A section of the daqdrc file (located in /opt/rtcds/caltech/c1/target/fb/ directory) had been commented out by Alex and never uncommented.  This section included the commands which actually make the fb record trends.

The section now reads as:

# comment out this block to stop saving data

#
start frame-saver;
sync frame-saver;
start trender;
start trend-frame-saver;
sync trend-frame-saver;
start minute-trend-frame-saver;
sync minute-trend-frame-saver;
start raw_minute_trend_saver;
#start frame-writer "225.225.225.1" broadcast="131.215.113.0" all;
#sleep 5;